XM-15B Bluetooth module (hereinafter referred to as module) meet Bluetooth SPP specification, compliant with the Bluetooth 2.1 + EDR standard, has two operating modes: command mode and data mode. Under data mode, divided into Master,Slave and loopback three operating roles. When the module is in command mode can perform all of the following AT commands, the user can send a variety of AT commands to the module, set parameters or send control commands. When the module is not connected to any device (blue light flash) in command mode, it is ready to receive AT commands. in command mode, the module can be connected or connect to other Bluetooth devices actively based on settings role. After the module is connected with other Bluetooth devices (blue indicator light), automatically enter data mode.

XM-15B core module is XM-05, base board built in power management chip with 5V and 3.3V TTL signal conversion circuitry, compatible with 3 / 3.3 / 5V several different voltage signal, the module TXD output pin high level is VCC-0.3V